A circuit (e.g., analog circuit) formed in a semiconductor device (semiconductor chip) includes a resistor. A resistor formed on a chip is a diffused resistor or a polysilicon resistor. A diffused resistor is a diffusion layer formed in a well (e.g., epitaxial layer). A polysilicon resistor is a polysilicon film formed on an insulation film (e.g., oxidized film), which is applied to a substrate region (e.g., epitaxial layer).
A resistor formed on a chip has an electrical resistance that changes in accordance with the potential difference between the resistor and a substrate region such as a well. Thus, the connection of one end of a polysilicon resistor to the substrate region or the like suppresses changes in the electrical resistance caused by such potential differences (refer to, for example, Japanese Laid-Open Patent Publication Nos. 2001-168651 and 2010-109233).
When forming a voltage dividing resistor with a diffused resistor or a polysilicon resistor, the voltage applied across the two terminals of a resistor would differ between resistors. Thus, when resistors have the same shape, the difference in the potential at the two terminals and the potential at the substrate region may differ between resistors. A diffused resistor and a polysilicon resistor change the extent to which their depletion layers spread in accordance with the difference of the potential at the substrate region and the potential at the terminals. Accordingly, in a circuit that series-connects two resistors, which are formed to have the same electrical resistance, and outputs a divisional voltage from a node between the two resistors, there may be a difference between the amount of change in the electrical resistance at the high potential side resistor and the amount of change in the electrical resistance at the low potential side resistance. Accordingly, even when two resistors are formed to have the same size and shape, changes in the electrical resistance ratio of the two resistors obstruct the generation of the desired divisional voltage.